/// <inheritdoc />
public object ConvertBack(object value,
Type targetType,
object parameter,
CultureInfo culture)
{
if (!this.initialized)
{
Initialize();
}
var message = this.errorText.ToString();
if (!(targetType == typeof(LengthPerUnitless) || targetType == typeof(LengthPerUnitless?)))
{
message += $"{GetType().Name} does not support converting to {targetType.Name}";
}
if (message != string.Empty)
{
message = message.TrimEnd('\r', '\n');
if (Is.DesignMode)
{
throw new InvalidOperationException(message);
}
return(message);
}
if (value == null)
{
return(null);
}
if (value is double)
{
return(new LengthPerUnitless((double)value, this.unit.Value));
}
var text = value as string;
if (string.IsNullOrEmpty(text))
{
return(null);
}
var unitInput = UnitInput ?? Wpf.UnitInput.ScalarOnly;
switch (unitInput)
{
case Wpf.UnitInput.ScalarOnly:
{
double d;
if (double.TryParse(text, NumberStyles.Float, culture, out d))
{
return(new LengthPerUnitless(d, this.unit.Value));
}
LengthPerUnitless result;
if (LengthPerUnitless.TryParse(text, NumberStyles.Float, culture, out result))
{
return($"#{text}#"); // returning modified text so that TypeConverter fails and we get an error
}
return(text); // returning raw to trigger error
}
case Wpf.UnitInput.SymbolAllowed:
{
double d;
int pos = 0;
WhiteSpaceReader.TryRead(text, ref pos);
if (DoubleReader.TryRead(text, ref pos, NumberStyles.Float, culture, out d))
{
WhiteSpaceReader.TryRead(text, ref pos);
if (pos == text.Length)
{
return(new LengthPerUnitless(d, this.unit.Value));
}
}
goto case Wpf.UnitInput.SymbolRequired;
}
case Wpf.UnitInput.SymbolRequired:
{
LengthPerUnitless result;
if (LengthPerUnitless.TryParse(text, NumberStyles.Float, culture, out result))
{
return(result);
}
return(text);
}
default:
throw new ArgumentOutOfRangeException();
}
}